September 11, 2023
Additive manufacturing or 3D printing, as it is commonly called, is a fast-evolving technology that has already revolutionised the innovation ecosystem with rapid product prototyping and manufacturing services. The journey from an idea to a 3D model to holding a physical prototype takes just a few days. Iterations are easier and cheaper to make without the use of expensive moulds or tools. Rapid product manufacturing has enabled the transition from a computer model to the final product without moulding, machining, casting, or fabricating.
The widespread use of 3D printing in aviation, automotive, healthcare, jewellery, ceramics, and many other sectors testify to its growing popularity. Thanks to a reduction in production costs, energy consumption and turnaround times, 3D printing companies have empowered both innovators and established businesses and minimised errors and inefficiencies.
However, to make the most of this technology that allows the freedom to create complex designs, facilitates mass customisation and manufacture on demand, boosts supply chain efficiency, and encourages sustainability, one needs to consider nine key factors.
There are several types of 3D printing technology, such as Stereolithography (SLA), Selective Laser Sintering (SLS), Digital Light Process (DLP), Multi Jet Fusion (MJF), PolyJet, Direct Metal Laser Sintering (DMLS), and Electron Beam Melting (EBM). All of these are advanced, industrial-level 3D printing systems.
SLA, or resin 3D printing, is considered the original 3D printing solution. It uses a laser or projector to cure liquid resin into hardened plastic. Used in manufacturing, engineering, dental applications, and entertainment, to name a few, SLA is much in demand because of its tight tolerance levels. It can accomplish accuracy to the level of ±0.1 mm. Post-processing methods, such as washing, sanding and polishing, spray coating and finishing with mineral oil are required in SLA to achieve the desired results.
SLS is useful in automotive, aerospace, medical and healthcare, consumer electronics, military and heavy industry.
DLP is largely used for recreating medical models and even precision medical devices.
MJF works for both functional prototypes and for end-use parts in the aerospace, medical, and consumer products industries.
DMLS parts can be found in commercial aircraft and rockets, ranging from simple brackets to complex turbine parts.
PolyJet is used in medical, packaging, toy and consumer goods industries.
EBM has use cases in aerospace, automotive, and medical/orthopaedic implant industries.
Each technology comes with its own strengths and weaknesses and differs from the rest in terms of the material it works on, surface finish, durability, manufacturing speed and cost. Identifying the right technology is the first step towards streamlining and expediting manufacturing, and ensuring quality, durability, and precision.
3D printing is truly versatile as it works on a wide range of materials. The most common printing material is plastic, followed by metals (stainless steel, bronze, nickel, aluminium, titanium), carbon fibre, resin, graphene, concrete and even biological matter. The choice of material has a direct bearing on the product’s performance, properties and appearance. For instance, Rapid Injection Moulding prototyping, ideal for research and developmental applications, is used on thermoplastics, thermoset silicones, nylon and polycarbonate. These materials make the cut due to their tensile strength, flexibility, toughness, electrical insulation, temperature and chemical resistance. Sheet metal prototyping, used for producing cost-effective, non-functional prototypes at a relatively high speed uses aluminium, stainless steel, copper, and magnesium in sheet forms. The common material for SLA is PA12/Nylon12. Derived from petroleum, it is known for its tensile strength, toughness, impact strength and ability to flex without fracture. They are ideal for the work SLA does: Printing parts with small features and managing to deliver products with very high resolution and accuracy.
Again, not all materials can lend themselves to intricate geometries. The ability of Polylactic acid (PLA), a thermoplastic monomer, to produce complex details has made it popular among artists and designers. Polyvinyl Alcohol (PVA), a water-soluble polymer, is often used as a support material for achieving complex designs in 3D printing, particularly for objects with overhangs or detailed internal structures.
Material selection should also take into account costs, printer’s specifications, post-processing requirements, sustainability and environmental impact.
One of the main advantages of 3D printing is design freedom. Free from traditional manufacturing techniques, one can push the envelope in terms of structure and design. An effective design seeks to strike a balance among size, resolution, thickness, orientation and choice of material. These key elements ensure the functional and aesthetic aspects of the product. However, while the most fantastic designs can come alive on the digital canvas, in reality physical models have to abide by the laws of physics. Moreover, not everything that looks great on the computer monitor can be successfully printed.
When it comes to design, the devil is in the details. The designer should keep in mind what amount of detailing the 3D printer can handle. This will require taking a call on whether smaller details are important to the design. Thoughtful design can save time and money by reducing assembly time and the number of components.
These are shapes/slopes that extend outward from the model with little or no support. The lack of a prop leaves overhangs prone to curling, delamination, sagging or collapsing. Printers can only do so much even with specialist overhang techniques. Some experts suggest to get rid of overhangs altogether. But if they are indeed a critical part of the design, keeping them at 45 degrees can minimise the need for support structures. At such an angle, every layer is in about 50 per cent contact with the layer below it and hence prints well.
Having said that, introducing support structures is an effective way to prevent overhangs and bridges from collapsing during printing. But this will also increase material usage, printing time, and post-processing work.
The thickness of the wall is an important parameter of quality in 3D printing. It determines the amount of material required to make the part, impacting the strength and weight of the structure. A thicker wall will obviously have greater strength to withstand heat and physical damage but it could result in poor surface finish. Inappropriate wall thickness can cause problems such as breaking off easily, cracking, and even parts not being printable. Therefore, it is important that the wall thickness of the model is assigned correctly. The minimum recommended thickness depends on the printing material, alignment, size, and the structure and geometry of the design.
In 3D printing, the materials undergo physical change as they are melted, sintered or scanned and then solidified. The rapid heating and cooling of materials can cause some parts to warp. In warping, the upper layers contract and pull on the lower, less solidified layers, thus lifting the first layer off the build platform and causing deformation. Poor ventilation, insufficient cooling fan speed, wrong type of adhesive, incorrect nozzle height, incorrect bed levelling, not cleaning the bed properly before printing and the wrong choice of 3D printing filaments only make matters worse.
Warping can be avoided if the 3D object has a large surface area relative to its volume. This can be achieved by reducing the thickness of the object or by increasing its surface area. A warm build plate also helps in preventing the filament from cooling too quickly and contracting. The risk of warping can be further mitigated with the use of a cooling chamber, which helps to regulate temperature and prevents uneven cooling.
Designing a spectacular 3D model may not be enough if one doesn’t know the best way to print it. This is where print orientation comes into play. It refers to the rotational orientation of the part, or the way in which the part is in contact with the build plate. In short, print orientation determines how the parts are printed on the build platform – it could be at an angle, horizontal, or vertical.
Orientation can also vary depending on the technology being used. One needs to keep in mind that 3D printed parts can be more fragile along the vertical axis than in the horizontal plane. This is especially true in the case of Fused Deposition Modeling (FDM) printers.
Having the right orientation saves significant print times and costs and helps get desired quality, functionality, and aesthetics. When it comes to large objects, orientation is required to maintain stability during the entire print time. A perfect orientation can be achieved by factoring in the build volume of the printer, identifying faces of the part that will provide good adhesion to the build plate, looking for ways to minimise support requirements to reduce complexity and material usage, and considering the amount of post-processing one is willing to do.
In 3D printers, resolution refers to the small movements the nozzles make while depositing material. The nozzles typically move on X, Y and Z axes, for lateral and vertical movements. Resolution has a direct effect on the quality of the printed objects. 3D printers with higher resolutions have smaller and more precise movements than others, ensuring better quality surface and smoother faces before post-processing. The thinner the layers, the more defined the details but the time taken to print will be much longer. SLA and SLS technologies offer higher resolution than FDM. Additionally, nozzle size, the stability of the metal frame anchoring the printer and print bed, the kind of material used, and the slicer and printer settings also influence quality.
3D printing is already catalysing a dramatic shift in industrial manufacturing technologies, away from the traditional methods that have had dangerous effects on the environment. In fact, an increased adoption of 3D printing is also fuelled because of its eco-friendliness. 3D printers need less materials than traditional manufacturing. They also use recyclable materials in closed loop, and the objects they produce are also recyclable. 3D printing can be deployed to tackle air quality, water and wastewater issues as well as to harness alternative energy.
3D printing will see a greater surge in popularity in the coming years, with rising support from governments and increased investments in the sector. The need for developing a robust start-up culture has prompted the US, UK, and Canada to aggressively promote research and adoption of 3D technology. With new applications for 3D technology gaining currency, public and private investors would like to further exploit its potential. Manufacturers are increasingly turning to 3D printing to tailor their products to specific customer needs. In this era of personalisation, it’s well-placed to offer the best solutions.
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